resonate-durable-sleep-scheduled-work-go

name

resonate-durable-sleep-scheduled-work-go

description

Implement durable sleep and recurring-work patterns in Go with Resonate — ctx.Sleep(time.Duration) inside workflows for timers, countdowns, reminders, and long-horizon delays that survive process restarts. The Go SDK has no top-level Schedule API yet; recurring work uses in-workflow ctx.Sleep loops or external cron → RPC. Use when a workflow must wait for hours or days, or when a function should run on a fixed schedule. Pre-release caveat: API surface may change before the first semver tag.

Resonate Durable Sleep + Scheduled Work — Go

Pre-release caveat. The Go SDK has no semver-tagged release yet, and — unlike the TypeScript/Rust SDKs — exposes no top-level Schedule API. This skill covers durable sleep (ctx.Sleep) and the available recurring-work patterns (in-workflow ctx.Sleep loops; external cron → RPC). Every code block is verified against develop/go.mdx, example-durable-sleep-go, and example-countdown-go at SDK commit 22076134651f.

Overview

Two related capabilities in the Go SDK:

1. Durable sleep inside a workflow — ctx.Sleep(d time.Duration) pauses execution; the worker process can exit and resume later without losing its place. The server holds the timer promise; cost is one promise record, not process uptime.
2. Recurring / periodic work — there is no resonate.schedule(...) in Go yet. Use an in-workflow ctx.Sleep loop (bounded or long-running periodic task owned by one workflow) or an external cron that fires r.RPC(...) on each tick.

Both patterns are durable: Resonate holds the continuation in its store, not in a long-running goroutine.

When to use

• Delays spanning minutes, hours, days, or weeks that must survive crashes
• Reminder sequences (7-day trial expiry, multi-stage onboarding drips)
• Countdown workflows that post a notification per tick
• Periodic jobs where an in-workflow loop is acceptable, or where an external scheduler already exists
• Any place you would reach for time.Sleep but need the work to survive a process restart

ctx.Sleep basics

ctx.Sleep takes a time.Duration and returns a *resonate.Future. Call f.Await(nil) to suspend until the timer fires — there is no value to decode.

// From example-durable-sleep-go/main.go
func sleepingWorkflow(ctx *resonate.Context, args SleepArgs) (string, error) {
    d := time.Duration(args.Secs) * time.Second

    f, err := ctx.Sleep(d)
    if err != nil {
        return "", fmt.Errorf("ctx.Sleep: %w", err)
    }
    // Await(nil) — no value to decode; suspends until the timer promise resolves.
    if err := f.Await(nil); err != nil {
        return "", fmt.Errorf("sleep await: %w", err)
    }

    return fmt.Sprintf("slept for %d second(s)", args.Secs), nil
}

Crash recovery. With a real Resonate server (-url=http://localhost:8001), killing the worker mid-sleep and restarting with the same promise ID resumes from the outstanding timer rather than restarting the workflow. The localnet transport runs state in process memory, so crash recovery requires a real server.

Duration encoding tip. time.Duration is int64 nanoseconds and round-trips through JSON as a bare number, which is opaque in promise payloads. Store durations as explicit seconds fields (as SleepArgs.Secs does) to keep stored promise data readable.

Reminder / multi-stage sleeps

Sequential ctx.Sleep calls are independent durable checkpoints. A crash mid-sleep resumes from that exact sleep on restart — earlier sleeps that already settled are skipped.

// Three-phase renewal reminder: 7 days out, 1 day out, renewal day.
func renewalReminder(ctx *resonate.Context, subID string) (struct{}, error) {
    // 7 days before renewal
    if f, err := ctx.Sleep(7 * 24 * time.Hour); err != nil {
        return struct{}{}, err
    } else if err := f.Await(nil); err != nil {
        return struct{}{}, err
    }
    if f, err := ctx.RPC("send-renewal-warning", subID); err != nil {
        return struct{}{}, err
    } else if err := f.Await(nil); err != nil {
        return struct{}{}, err
    }

    // 6 more days (1 day before renewal)
    if f, err := ctx.Sleep(6 * 24 * time.Hour); err != nil {
        return struct{}{}, err
    } else if err := f.Await(nil); err != nil {
        return struct{}{}, err
    }
    if f, err := ctx.RPC("send-final-warning", subID); err != nil {
        return struct{}{}, err
    } else if err := f.Await(nil); err != nil {
        return struct{}{}, err
    }

    // 1 more day — renewal day
    if f, err := ctx.Sleep(24 * time.Hour); err != nil {
        return struct{}{}, err
    } else if err := f.Await(nil); err != nil {
        return struct{}{}, err
    }
    f, err := ctx.RPC("charge-renewal", subID)
    if err != nil {
        return struct{}{}, err
    }
    return struct{}{}, f.Await(nil)
}

Countdown loop (in-workflow recurring pattern)

The example-countdown-go canonical example shows the real in-workflow loop pattern: dispatch the side effect via ctx.RPC (durable, checkpointed), then ctx.Sleep between ticks.

// From example-countdown-go/main.go — adapted for clarity.
func countdown(ctx *resonate.Context, args CountdownArgs) (CountdownResult, error) {
    sent := 0
    for i := args.Start; i > 0; i-- {
        // Side effect lives inside ctx.RPC so it's checkpointed — won't double-fire on resume.
        f, err := ctx.RPC("notify", NotifyArgs{Count: i, URL: args.NotifyURL})
        if err != nil {
            return CountdownResult{}, err
        }
        var r NotifyResult
        if err := f.Await(&r); err != nil {
            return CountdownResult{}, fmt.Errorf("notify %d: %w", i, err)
        }
        sent++

        if i > 1 {
            s, err := ctx.Sleep(time.Duration(args.StepSeconds) * time.Second)
            if err != nil {
                return CountdownResult{}, err
            }
            if err := s.Await(nil); err != nil {
                return CountdownResult{}, fmt.Errorf("sleep before %d: %w", i-1, err)
            }
        }
    }
    return CountdownResult{Sent: sent}, nil
}

A crash during the ctx.Sleep between ticks resumes mid-loop — completed ctx.RPC ticks short-circuit on replay; the pending sleep re-suspends until its timer fires.

Long-horizon sleeps are cheap

Sleep duration is unbounded. Cost is roughly one promise record; the process does not need to stay alive.

// Sleep for months — the process can exit and the timer holds in the server.
func birthdayGreeting(ctx *resonate.Context, args BirthdayArgs) (struct{}, error) {
    f, err := ctx.Sleep(args.UntilBirthday) // weeks or months ahead
    if err != nil {
        return struct{}{}, err
    }
    if err := f.Await(nil); err != nil {
        return struct{}{}, err
    }
    gf, err := ctx.RPC("send-birthday-email", args.UserID)
    if err != nil {
        return struct{}{}, err
    }
    return struct{}{}, gf.Await(nil)
}

Scheduled / recurring work without a Schedule API

resonate.schedule(...) does not exist in the Go SDK. The go.mdx docs include an explicit callout: "No Schedule or top-level promises sub-client yet." Do not translate Rust or TypeScript schedule examples directly — the API is absent.

Two available substitutes:

Pattern 1 — In-workflow ctx.Sleep loop

A workflow that loops indefinitely (or for a bounded count) and sleeps between iterations is a self-contained recurring job. The loop is fully durable — a crash mid-sleep resumes at the current iteration.

// Periodic cleanup job: runs every intervalDays days, indefinitely.
func periodicCleanup(ctx *resonate.Context, args CleanupArgs) (struct{}, error) {
    for {
        // Side effect checkpointed in ctx.Run — won't double-fire on replay.
        f, err := ctx.Run(runCleanup, args)
        if err != nil {
            return struct{}{}, err
        }
        if err := f.Await(nil); err != nil {
            return struct{}{}, err
        }

        // Durable sleep until next run.
        s, err := ctx.Sleep(time.Duration(args.IntervalDays) * 24 * time.Hour)
        if err != nil {
            return struct{}{}, err
        }
        if err := s.Await(nil); err != nil {
            return struct{}{}, err
        }
    }
}

Start once with a stable promise ID:

// Invoke from the ephemeral world — deduplicated on the ID, so safe to re-run on deploy.
h, err := cleanupFn.Run(ctx, "periodic-cleanup-prod", CleanupArgs{IntervalDays: 7})

When to use: bounded or long-running periodic task owned by exactly one workflow; interval driven by business logic inside the workflow.

Pattern 2 — External cron → r.RPC

Keep the schedule outside Resonate (OS cron, Cloud Scheduler, GitHub Actions, Kubernetes CronJob). Each tick calls r.RPC (or the resonate invoke CLI) to create a durable invocation.

// cron-trigger/main.go — runs on every cron tick; idempotent on stable ID.
func main() {
    r, err := resonate.New(resonate.Config{URL: os.Getenv("RESONATE_URL")})
    if err != nil {
        log.Fatalf("resonate.New: %v", err)
    }
    defer func() { _ = r.Stop() }()

    // Stable ID for today's run — deduplicates if the cron fires twice.
    today := time.Now().UTC().Format("2006-01-02")
    id := fmt.Sprintf("nightly-recon/%s", today)

    ctx := context.Background()
    h, err := r.RPC(ctx, id, "nightly-reconciliation", ReconArgs{Date: today})
    if err != nil {
        log.Fatalf("RPC: %v", err)
    }
    var result ReconResult
    if err := h.Result(ctx, &result); err != nil {
        log.Fatalf("Result: %v", err)
    }
    log.Printf("reconciliation done: %+v", result)
}

When to use: the schedule already lives in an external system; per-firing invocations are independent (no loop state carried across ticks); or the interval must be changed without redeploying a long-running workflow.

CLI equivalent (no code trigger needed):

resonate invoke nightly-reconciliation --id "nightly-recon/$(date +%F)" --data '{"date":"2026-06-10"}'

Distinct Go idioms

• f.Await(nil) — sleep futures carry no value; pass nil to Await (unlike ctx.Run/ctx.RPC futures where you decode into a pointer).
• time.Duration — all sleep durations are native Go durations (24*time.Hour, time.Minute, etc.); no raw millisecond integers, no cron strings.
• ctx.Sleep vs time.Sleep — time.Sleep inside a durable function is not durable (lost on crash, blocks the goroutine for its full duration). Always use ctx.Sleep for anything you need to survive a restart.
• Options struct last — ctx.Sleep takes only a time.Duration; no options struct. ctx.Run/ctx.RPC accept an optional trailing RunOpts/RPCOpts struct.
• Localnet requires NoopHeartbeat{} — localnet.NewLocal(...) has no HTTP endpoint; the default AsyncHeartbeat will error. Always pair localnet with Heartbeat: resonate.NoopHeartbeat{}.

Avoid

• time.Sleep inside a durable function — ephemeral; lost on crash; holds the goroutine for the full duration. Use ctx.Sleep.
• Un-checkpointed side effects before a sleep — any code that runs before a ctx.Sleep (or any other durable boundary) re-executes on resume. Wrap observable side effects (DB writes, emails, webhooks) in ctx.Run/ctx.RPC so the durable promise records the result and short-circuits replay.
• Assuming a Schedule API exists in Go — it does not; translating Rust or TypeScript resonate.schedule(...) code verbatim will not compile. Use the two patterns above.
• Clock precision assumptions — ctx.Sleep(24*time.Hour) firing in 23–25h is within spec (server/worker drift). Don't treat variance of ±1h as a bug for long-horizon sleeps.
• Raw time.Duration nanoseconds in promise payloads — store durations as explicit integer fields (seconds, minutes) to keep promise data human-readable across crashes and inspections.

Related skills

• resonate-basic-durable-world-usage-go — ctx.Run, ctx.RPC, ctx.Promise fundamentals; the same Context the ctx.Sleep API lives on
• durable-execution — foundational replay semantics; sleep is a durability checkpoint by design
• resonate-durable-sleep-scheduled-work-typescript — TypeScript sibling; has resonate.schedule() (cron strings, ms durations)
• resonate-durable-sleep-scheduled-work-rust — Rust sibling; has resonate.schedule() (cron strings, std::time::Duration)
• SDK gap note: both Go and Python lack a top-level schedule() as of this writing; TypeScript and Rust have it. If porting a scheduled workflow from Rust/TypeScript to Go, replace resonate.schedule(...) with one of the two patterns in the "Scheduled / recurring work" section above.